<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport"
        content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
<div id="app">
  <h1 style="width: 200px">虚拟dom</h1>
  <p :class="{'add':foo>3}">{{foo}}</p>
</div>
<script src="../../dist/vue.js"></script>
<script>
  var app = new Vue({
    el: '#app',
    data: {foo: 1},
    mounted() {
      // setInterval(() => {
      //   this.foo += 3
      // }, 1000)
    }
  })
</script>
</body>
</html>
